This is a placebo controlled clinical trial to assess the utility of light therapy as a sufficient treatment for excessive daytime sleepiness in patients with Prader-Willi Syndrome

This is a prospective, placebo controlled, open label clinical trial that examines light therapy as a treatment for excessive daytime sleepiness in patients with Prader-Willi syndrome. Subjects are assessed for changes in mood, behavior, body weight, and hyperphagia during visits. All visits are conducted remotely. There are a total of 8 visits occurring over the course of 8 weeks. After the first visit, all study visits occur on a weekly basis.

Individuals between the ages of 6-18 years old with diagnosis of PWS confirmed by genetic testing will be screened for enrolment by the study team.

Inclusion Criteria:

• Diagnosis of PWS confirmed by genetic testing
• Score of 12 or above on the Epworth Sleepiness Scale (ESS).

Exclusion Criteria:

• Subjects with an eye condition that could be negatively affected by bright light such as patients with a history of retinal damage or patients needing photosensitizing medications
• A history of previous treatment with LT
• Patients presenting with active psychosis or mania